title: Expression profiling of genes involved in ascorbate biosynthesis and recycling during fleshy root development in radish.
abstract: Ascorbate is a primary antioxidant and an essential enzyme cofactor in plants, which has an important effect on the development of plant root system. To investigate the molecular mechanisms of ascorbate accumulation during root development and reveal the key genes of the ascorbate biosynthesis and recycling pathways, the expression of 16 related genes together with ascorbate abundance were analyzed in the flesh and skin of radish (Raphanus sativus L.) fleshy root. The content of ascorbate decreased with root growth in both the flesh and skin. Expression of GDP-d-mannose pyrophosphorylase, GDP-d-mannose-3',5'-epimerase and d-galacturonate reductase were also decreased and correlated with ascorbate levels in the flesh. In the skin, the expression of GDP-d-mannose pyrophosphorylase and l-galactose dehydrogenase was correlated with ascorbate levels. These results suggested that ascorbate accumulation is affected mainly by biosynthesis rather than recycling in radish root, and the l-galactose pathway may be the major biosynthetic route of ascorbate, and moreover, the salvage pathway may also contribute to ascorbate accumulation. The data suggested that GDP-d-mannose pyrophosphorylase could play an important role in the regulation of ascorbate accumulation during radish fleshy taproot development.
authors.affiliation: National Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Horticultural Crop Biology and Genetic Improvement (East China), Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, PR China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Xu
authors.forename: Xianwen
authors.initials: X
authors.lastname: Zhu
authors.forename: Yinglong
authors.initials: Y
authors.lastname: Chen
authors.forename: Yiqin
authors.initials: Y
authors.lastname: Gong
authors.forename: Liwang
authors.initials: L
authors.lastname: Liu
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D005690:Galactose / Q000235:genetics / Q000378:metabolism; D005691:Galactose Dehydrogenases / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D017343:Genes, Plant; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; D006005:Phosphorylases / Q000235:genetics / Q000378:metabolism; D063245:Plant Development / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism*; D031224:Raphanus / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome
chemical_list: D000975:Antioxidants; D010940:Plant Proteins; D000429:Alcohol Oxidoreductases; D005691:Galactose Dehydrogenases; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; C477073:D-galacturonate reductase; C047959:galactose dehydrogenase; D006005:Phosphorylases; D001205:Ascorbic Acid; D005690:Galactose
keywords: 4,7-diphenyl-1,10-phenanthroline; AO; APX; AsA; Ascorbate; BT; DHAR; EtOH; GDP-l-galactose-1-phosphate phosphorylase; GDP-mannose pyrophosphorylase; GDP-mannose-3′,5′-epimerase; GGP; GLDH; GME; GMP; GPP; GR; GalDH; GalUR; Gene expression; MDHAR; MIOX; PGI; PMI; PMM; R/S; ROS; RT-PCR; Raphanus sativus L.; Root development; T-AsA; TCA; ascorbate; ascorbate oxidase; ascorbate peroxidase; d-galacturonate reductase; dehydroascorbate reductase; ethyl alcohol; glutathione reductase; l-galactono-1,4-lactone dehydrogenase; l-galactose dehydrogenase; l-galactose pathway; l-galactose-1-phosphate phosphatase; monodehydroascorbate reductase; myo-inositol oxygenase; phosphoglucose isomerase; phosphomannose isomerase; phosphomannose mutase; reactive oxygen species; reverse transcription and polymerase chain reaction; root–shoot ratio; total ascorbate; trichloroacetic acid